PDMS1 SPME2 SAMPLING

Danny Reible – University of TexasHeidi Blischke - GSI

1 Polydimethyl siloxane2Solid Phase Microextraction

Solid Phase Microextraction (SPME) Sampler

A ) SPME Fiber Close - up

B ) Complete SPME Device

C ) Insertion into Sediment

Data Quality Objectives Determine whether exceedances of performance standards from

the record of decision and/or comparison criteria of more recent water quality criteria from EPA have occurred at any of the locations sampled. For this objective to be successful, low level detection limits for carcinogenic PAHs are necessary.

Assess concentration gradients between near surface and at depth. For this objective to be successful, samples from discrete intervals within the vertical sediment cap profile are required.

Define trends in interstitial water concentrations that may provide early warning signs of potentially significant contaminant migration through a cap (i.e. migration that may lead to exceedances of performance standards in the near future). For this objective to be successful, detection limits must be sufficiently low to detect PAHs to identify trends.

SPME Decision Logic

PAH< surface thresholdPAH> deep threshold PAH>thresholds

PAH< surface threshold

PAH<deep threshold

PAH> surface threshold PAH<deep threshold No Evidence of

Cap breakthrough

AWQS noncompliant. No Evidence of Bottom-Up breakthrough

Currently Compliant with AWQS

AWQS noncompliant. Evidence of Bottom-Up breakthrough

Fiber-Water Partition Coefficient

Average deviation <5%

Average deviation ~12%

y = 0.757x + 0.513R² = 0.970

3.0

3.5

4.0

4.5

5.0

5.5

6.0

3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0

Log K

fw

Log Kow

Log Kfw

0.839*LogKow+0.117

Linear (Log Kfw)

f fw pwC K C

Detection Limits,Linearity, and Coefficient of Variation

Kfw

Concentration

Magnification

r2

Linearity COV PDMS

PDMS MDL µg/L

*

PDMS MDL µg/L **

Naphthalene 78.5 0.1547 88.8% 0.3332 0.07207DBF 4027 0.985 10.0% 0.0123 0.00265

2-MNP 2591 0.9817 70.2% 0.0268 0.00580Fluorene 4227 0.9984 5.6% 0.0697 0.01508

Acenaphthene 3662 0.9996 14.1% 0.0315 0.00680Phenanthrene 10938 0.9973 1.3% 0.0076 0.00164

Anthracene 10810 0.998 18.1% 0.0075 0.00161Fluoranthene 30327 0.9985 9.9% 0.0025 0.00054

Pyrene 35394 0.9987 8.1% 0.0021 0.00046Chrysene 52898 0.9967 19.1% 0.00048 0.00010

Benz[a]anth 85097 0.9978 3.9% 0.00011 0.00002Benzo[b]fluoranthene 119712 0.9945 11.6% 0.00011 0.00002Benzo[k]fluoranthene 120458 0.9781 8.0% 0.00002 0.00000

Benzo[a]pyrene 122795 0.9755 5.8% 0.00005 0.00001Dibenz[a,h]anthracene 142042 0.9241 5.5% 0.00007 0.00001Benzo[ghi]perylene +

Indenopyrene 161013 0.9179 7.0% 0.00010 0.00002

Average w/o Naphthalenes 0.98279 9.1%+/-5%

Conventional Detection Limit 0.0118COV Conventional Analysis 10%+/-8%

* 3cm of 10 um layer on 210 um core**1 cm of 30 um layer on 1000um core

Pros: Lower detection

limits for CPAHs – well below NRWQC

Early warning of increasing concentrations

Cons: Naphthalenes have

higher detection limits

Detection limit function of hydrophobicity

Method MDL Comparison

Detection Limits in smaller fiber (not used at M&B)

Fall 2010 SPME Sampling

24 SPME passive samplers were installed: 2 surface water (background) locations 22 sediment cap monitoring locations

After 7 days of exposure, 23 samplers were retrieved: One sampler was lost (Location 4)

SPME Installation

SPME Installation and Depths Target sample depths:

6” below the top of the armoring layer 6” into the sand cap 12” into the sand cap

The actual sample depths varied slightly from the target depths.

Sample Processing Pre deployment

Fiber and sampler cleaning (solvent rinse) Fiber placement in sampler

Deployment Via divers except at shore Difficulty in achieving target depths in armored

area Retrieval after 1 week

Sectioned on site and placed into pre-filled autosampling vial

Shipped back to UT and analyzed directly

Deployment – 1 week Is it adequate?

Static Lab Expts Anacostia River

Slow Equilibrium? Low cap sorption

capacity Speed

Equilibrium? Tides Groundwater flow

PAH Kinetics in Bare Fiber

Time (d)

0 5 10 15 20

Fib

er

co

nc ( g

/L)

0

100

200

300

400

500

600Phe

Chrysene

B[b]F

B[a]P

Deployment – 1 week Is it adequate?

Estimation Performance Reference

Compounds Time Series Two different size fibers

Puget Sound data shown 7 days Tidal system but no

shoreline Nonsorbing cap

Method Uncertainties PDMS

Fiber-water partition coefficient (error ~ 10%)) Equilibrium

PRC or two size fibers (failed in first application to site) Experience suggests near equilibrium for low MW PAH but high

MW PAH may be underestimated Maximum underestimation ~factor of 2-3

Site specific kinetic evaluation is recommended or use of thin fibers

Conventional pore water sampling (Henry’s probe) Poor detection limits (often near criteria) Poor depth control Potential for solids resuspension and sampling artifacts Includes both dissolved and colloidally/particulate bound

contaminants

SPME most biologically relevant

R² = 0.8723

0

5

10

15

20

25

30

35

0.0 1.0 2.0 3.0 4.0

Tis

sue

Con

cent

ratio

n (u

g/kg

)

Pore Water Concentration (ng/L)

Pore Water Concentration (21 day SPME)

R² = 0.4422

0

5

10

15

20

25

30

35

0.0 100.0 200.0 300.0 400.0 500.0 600.0

Tis

sue

Con

cent

ratio

n (u

g/kg

)

Pore Water Concentration (ng/L)

PAH Tissue Correlation Concentration (Centrifugation)

R² = 0.7583

0

5

10

15

20

25

30

35

0.0 0.5 1.0 1.5 2.0

Tis

sue

Con

cent

ratio

n (u

g/kg

)

Pore Water Concentration (ng/L)

Pore Water Concentration (2 day SPME)

R² = 0.2703

0

5

10

15

20

25

30

35

0.0 5000.0 10000.0 15000.0 20000.0 25000.0 30000.0

Tis

sue

Con

cent

ratio

n (u

g/kg

)

Sediment Concentration (ug/kg OC)

OC Normalized Sediment Concentration

M&B 2010 Results Summary 35% of possible compound detects measured LPAHs were detected more frequently than other

PAHs Acenapthene and phenanthrene were detected in

all samples Only LPAHs were detected in the two background samples The three most hydrophobic compounds were not

detected in any samples (likely due to low mobility) Dibenz(a,h)anthracene Benzo(g,h,i)perylene Indeno(1,2,3-cd)pyrene

2010 Near Shore Vertical Profiles: Pyrene

Near shore vertical concentration profiles are fairly uniform.

Concentrations either stay the same or increase slightly with depth.

Possibly due to mixing caused by tidal fluctuations.

2010 Off Shore Vertical Profiles: Pyrene

Off shore vertical concentration profiles display greater gradients than near shore profiles.

Concentrations increase with depth.

Comparison- 2009 & 2010 SPME

Individual PAH concentrations were compared for Locations 5, 9, 12, and 16. All concentrations increased at Location 5. Locations 9 and 16 showed some concentrations

increasing and some decreasing Most concentrations decreased at Location 12.

y = 416.93x1.2574

R² = 0.9271

0.000001

0.00001

0.0001

0.001

0.01

0.1

1

10

100

0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10

SPM

E 20

10

SPME 2009 (Location 5)

y = 0.01x0.5575

R² = 0.8391

1E-06

1E-05

0.0001

0.001

0.01

0.1

1

10

100

0.000001 0.00001 0.0001 0.001 0.01 0.1 1 10

SPM

E 20

10

SPME 2009 (Location 12)

Summary of Results 2010

1E-08

0.0000001

0.000001

0.00001

0.0001

0.001

0.01

0.1

1

10

0 5 10 15 20 25

Nor

mal

ized

pore

wat

er c

oncn

sample locations

Naphthalene

Fluorene

Anthracene

Fluoranthene

pyrene

chrysene

B[a]A

B[b]F

B[k]F

B[a]P

NRWQC

Comparison to NRWQC Only one exceedance: chrysene at location 5

about 12 inches into the sand portion of the cap 18-24 inches below sediment water interface. 0.035 µg/L (duplicate 0.005 µg/L)

Two other detections approached NRWQC at the deepest sample intervals: Benz(a)anthracene was 80% of the criterion at Location 5 Benz(a)anthracene was 60% of the criterion at Location

16 All other compound concentrations at all other

locations and depths were well below the NRWQC.

y = x

R² = 1

All Data Fity = 0.9353x0.9821

R² = 0.9691Interarmoring

y = 0.9795x0.9852

R² = 0.9742

6" Subarmoringy = 1.0331x0.9903

R² = 0.9739

12" Subarmoringy = 0.8512x0.9767

R² = 0.9611

1.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1.00E+00

1.00E+01

1.00E+02

1.00E+03

1.00E+04

1.00E-06 1.00E-05 1.00E-04 1.00E-03 1.00E-02 1.00E-01 1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04

B sa

mpl

es P

AH c

once

ntra

tions

(ug/

L)

A samples PAH Concentrations (ug/L)

Comparison of Duplicates- All samplesIA data

6" Subarmoring

12" Subarmoring

Comparison of Adjacent Duplicates

Comparison of Adjacent Sites 5, 17

0.0001

0.001

0.01

0.1

1

10

100

0.0001 0.001 0.01 0.1 1

Site

5 u

g/L

Site 17 ug/L

-6 cm

-7 cm

-18 cm

parity

Site 5 ~100 times higher than adjacent site (local contamination)

Conclusions - 2010 Sampling 35% of possible compound detections

compared to less than 10% in conventional approaches 50%+ in preceding years suggesting general downward trend

LPAHs detected more frequently than LPAHs No comparison criteria exceeded in inter-armoring or 6

inches into sand cap One cPAH (chrysene) exceeded at 12 inches into sand cap

at Location 5 Few increases noted at 12 inches into sand cap in 2010

samples relative to 2009 – will get trend data in 5-year sampling events for early warning

Sediment cap is protective of surface water and functioning as designed

Conclusions: SPME versus Conventional Sampling for M&B Long-Term Monitoring

SPME Detection limits << criteria More detections from which to draw conclusions Higher spatial resolution (no dilution by

withdrawing excessing water volume) Eliminates particulate and colloidal artifacts Minimal sample processing 1 day placement, 1 day retrieval vs 1 week

conventional sampling requirement More biologically relevant indicator